Many kinds of couplings for pipes exist in the art. One kind of prior art coupling for pipes is illustrated in FIG. 1. It is noted that throughout the specification and claims, the term “pipe” encompasses any kind of generally cylindrical object, and the terms “clamp” and “coupling” are used interchangeably.
The prior art coupling includes a cylindrical housing 1 with an annular flange 2. The end face of annular flange 2 is formed with an inclined face 3 against which a seal 4 is placed. Seal 4 is made of rubber or other suitable elastomer. A clamping ring 5 is clamped to annular flange 2 with a plurality of axial fasteners 6 circumferentially spaced about the coupling. Fasteners 6 (e.g., bolts and nuts) pass through holes 7 and 8 formed in annular flange 2 and clamping ring 5, respectively. Clamping ring 5 has an inclined axial lip 9 that presses against the seal 4, so that seal 4 is sandwiched between annular flange 2 and clamping ring 5. The tightening force on the inclined surfaces of face 3 and lip 9, provides a wedging radial force on seal 4 so that seal 4 radially tightens against a pipe 11 placed in the coupling. This seals the coupling on the pipe.
There are many kinds of mechanical joint restraints and other accessories in the prior art that incorporate the above type of coupling. These restraints have been used on valves, fittings, hydrants, and other pipe connections where it is necessary to secure together or restrain two members which tend to separate in response to fluid pressure from within. Typical uses for such restraints are sewers and pipe systems for water distribution. One drawback of the prior art restraints is the need to have an inventory or supply that spans a range of pipe diameters.